Threats to bees

​What Bees Need and Don’t Need

Honeybees are definitely independent. They can fly for miles for food, they can defend themselves against attack, and they can even survive the harshest winters, despite being very vulnerable to cold. But despite being so tough, there are some basic things bees need to survive, and plenty of problems that can befall them. Let’s briefly go over what bees need and don’t need.

What bees need has been covered for the most part in Installing and Preparing your Beehive. Bees need a nearby source of water for cooling the hive and dissolving crystallized honey. They need peace from loud noises and disturbances. They need an ample source of nectar and pollen in the summer - the closer the better - and they need warm weather in the summer in which they can collect it. In the winter they have to keep their body temperatures above 57F, which means they absolutely need shelter and enough stored honey that they can stay inside and keep warm for months.

The list of what bees don’t need is pretty extensive. From too much heat to too much cold, from a dead queen to an overzealous beekeeper, bees face a lot of problems. In a later article we’ll cover them all, but for the moment let’s talk about four big problems that honeybees face the world over: disease, pests, pesticides, and Colony Collapse Disorder.

Colony Collapse Disorder

Colony Collapse Disorder, often called CCD, is something of a mystery. When it happens, an otherwise healthy seeming colony suddenly falls apart. All or almost all the worker bees disappear, leaving behind the queen, brood, and maybe a few nurse bees. The thousands of missing workers don’t die (at least not in the hive). They simply disappear. To make things stranger, all the food stores they behind remain untouched. Usually an unprotected hive is a prime target for robbing by other colonies, but outside bees avoid colonies affected by CCD, at least for the first few days.

This phenomenon began in the autumn of 2006, though it’s not the first widespread loss of honeybee colonies. In the 1880s, the 1920s, and the 1960s, honeybee colonies took serious hits. In 1995, Pennsylvania beekeepers lost over half of their colonies. Not enough evidence exists, however, to know whether or not these losses are related to CCD.

What we do know is that an average of ﻿30% of colonies have died from CCD since 2006, with some beekeepers losing as much as 90% of their colonies virtually overnight.

A huge amount of study is going into uncovering the possible causes of CCD, but unfortunately it’s not proving so easy to figure out. A wide number of culprits have been brought up. It’s hard to be sure, though, because no one thing is always present when CCD takes place, and some things, while maybe not the direct cause, can really weaken the colony and make it more vulnerable to whatever does cause CCD.

One possibility is disease. Honeybees are vulnerable to quite a few diseases, as we’ll see in a minute, and they can be present in colonies that suffer from CCD. Though scientists are looking especially closely at Nosema and Paralysis, no one disease has been linked directly to CCD. If disease does have a bearing on CCD, it is likely either a yet unknown disease, a special cocktail of multiple diseases, or a simple weakening of the colony due to disease in general that makes it more vulnerable to a different, unknown cause.

Varroa mites are being given a serious look because of their frequent presence in CCD colonies. These mites are parasites that clamp down on the bees’ backs and feed off of them. It is possible that this weakening is the cause of CCD, but it’s more likely the transmission of a pathogen carried by the mites or an opening to infection in the wound they create on the bee’s back. Of course, varroa mites haven’t been directly linked, but they are pretty suspicious and very bad for bees in their own right.

Another possible cause is a lack of genetic diversity. There aren’t very many queen breeders in the US, which means the genetic diversity of queens is pretty low. Since an entire colony is descended from a single queen, this means that all honeybees are very genetically homogeneous, and most are very closely related. This is called a “genetic bottleneck,” and it can lead to serious problems when it comes to disease. Genetically diverse populations are constantly introducing new resistances to disease, but a family with a weakness that keeps it in the family will always have that weakness. This could be leading to susceptibility to some unknown cause of CCD.

Environmental stress could also be causing CCD. Environmental stress is a name that can be given to a number of things, from low quality pollen to lack of nutrition or diversity in pollen, to the widespread use of pesticides. Some people also believe genetically modified crops are to blame.

Management stress is another possibility. Agriculture relies extremely heavily on honeybees for pollination, and there’s a theory that this reliance is starting to take its toll. In order to ensure pollination, many beekeepers move their bees from location to location, allowing the bees to forage on commercial crops. Bees, of course, don’t naturally move from place to place like this, and the constant movement may be pushing them over the edge. Similarly, the overcrowding of hives in a small area to ensure all the flowers are pollinated may be harming the bees due to poor nutrition or the stress of flying extra miles to forage. Of course, not all bees are used for commercial pollination, and their hives are still vulnerable to CCD.

So what is causing CCD? There seems to be no clear right answer at the moment. In all likelihood, it’s some kind of combination of the factors listed above and not just one. If it is just one thing, odds are good that it’s something we haven’t even thought of yet.

Unfortunately, since we rely so heavily on bees for our food, CCD is bad news for everyone, not just beekeepers. Farmers pay for bees to pollinate their crops, and the fewer bees there are the more pollination is going to cost. If CCD continues, we can expect a serious spike in food prices.

How can you protect your bees from CCD? Since we don’t know its cause, it’s impossible to truly prevent it, and even the most experienced beekeepers can be devastated by it. The best thing you can do is to try to keep your colony healthy. Treat for mites, make sure your bees have good food and water sources, and avoid using pesticides. If you notice a colony collapsing, don’t try to bolster it with extra bees. The sick bees are likely to infect the healthy ones. If a colony has collapsed, don’t reuse the hive. It might also be infected.

Disease

Disease is a very big concern in beekeeping, particularly considering that some of them are under suspicion of causing CDC. Here are some of the main diseases, how to recognize them, and what to do about them.

American Foulbrood is extremely contagious and a huge threat to honeybee populations. It only affects worker, queen, and drone larvae that is less that 2 ½ days old, but that’s more than enough to wreak havoc. The larva eats the spore-forming bacteria, and it multiplies inside it until it dies. The larva turn from their healthy, succulent white to a flattened brown. Eventually the dead larva hardens to a small, black scale inside its cell. This scale is teeming with new foulbrood spores. You can usually spot American Foulbrood from a spotty mix of capped and uncapped brood, with the capped cells having punctured or sunken tops. You can also detect it in dangling remains of decomposed pupas hanging down from the tops of their cells or by inserting a small stick into a dead brood cell. If the brood stretches back out with the stick with a gluey consistency, you probably have an American Foulbrood infection. American Foulbrood spores can stay active in beekeeping equipment for as long as 40 years and are extremely resistant to treatment. If you have an American Foulbrood infection, the only course of action is to destroy the colony and burn the equipment. Terramycin is a drug that can be applied monthly to prevent the appearance of the disease. Check with your state to see if its use is legal there.Image: burning hives.

European Foulbrood is another bacterium that gets into food and populates inside the brood. It usually appears in spring and early summer and can be picked out by a spotty pattern of capped and uncapped brood. Brood killed by it don’t take on the gluey consistency associated with American Foulbrood. Unlike American Foulbrood, European Foulbrood is not a death sentence for the colony. It will sometimes disappear with a strong nectar flow. If it’s not going away, the best course of action is to requeen the colony - this gives the bees a lag time between laying to clear out the infected brood remains.

Chalkbrood is a fungus that enters the brood through food. It waits until the brood is sealed in its cell, then it grows and takes over the larva. Larva killed by chalkbrood take on an opaque, white appearance, hence the name. Chalkbrood is usually found in late spring on the fringes of the frames. You’ll know you have it if you see these little chalk nub bodies outside the hive entrance, where worker bees have discarded them. There’s no real treatment, though requeening has been known to help. If the workers manage to remove all the infected brood, the colony should survive.

Sacbrood is a virus that is not usually a problem as it affects only a small number of brood. The brood dies after its cell is capped, and its body takes on a liquidy consistency inside a tough outer skin. There’s no treatment, though requeening can help.

Nosema forms spores inside the digestive tract of adult bees. It is, basically, bee diarrhea. It causes bees to defecate inside or down the front of the hive, which spreads the disease more. It shortens worker bees’ lifespans and ability to make royal jelly, and if it infects the queen it can seriously interfere with laying. Healthy, well fed hives with young queens are less likely to get nosema. Fumagillin is a drug that can be used on young or overwintering hives.

Paralysis comes in two forms: chronic bee paralysis and acute bee paralysis. It can come from eating pollen of certain plants and fermented stored pollen. It’s easy to detect, and the bees lose their hair, take on a greasy look, and tremble. A colony can recover from paralysis naturally, but if it doesn’t, you should requeen with different strain, as weakness to it is often genetic.

Pests

On top of diseases, honeybees have ﻿plenty of enemies in nature. They’re far from helpless, of course, and can fend for themselves very well, but it’s good to know what your bees are up against.

The stories are true - bears really do love honey, and they’ll go to great lengths to get it, including smashing your equipment beyond repair. If bears are a problem in your area, consider raising your hives on a bear proof platform or surrounding them with an electric fence. If a bear has already found your hives, unfortunately, it will keep coming back for more. Once this happens, the only real course of action is to move the hives.

Mice are a problem in winter, when they’ll crawl inside a nice warm beehive to build their nests. A mouse will stay in the corner of the hive, well away from the bees, but it will chew through wax and frames to make room, and the smell of its urine will put your bees off the hive in the spring. Keep mice out by adding an entrance reducer in the autumn. If you find a mouse in your hive, chase it out and remove its nest and any frames it’s chewed.

Wax moths lay their eggs in beehives and stored frames, where they lay their eggs. The resulting wax moth caterpillars can wreak havoc, tunneling through wax foundation in search of pollen and brood. A strong hive will simply throw the eggs out, but weak colonies and especially stored frames are at risk. Store your frames either in very cold temperatures or with granules of paradichlorobenzene (PBD).

Wasps, hornets, and yellowjackets will sometimes kill bees at the entrance to the hive or out in the wild. The best way to deal with them is to find and chemically destroy their nest. Alternatively, you can move your hives away from the nest or use an entrance reducer to help the bees better guard against their attackers.

Flies such as the Southern Bee-killer and the Texas Bee-killer are known to eat bees. If they come after your hive, there’s nothing to do but move it to a new spot.

The ﻿Small Hive Beetle will infiltrate the hive where it feeds on pollen and lays eggs, sometimes overrunning a colony. If your hive has an infestation, treat it with the appropriate pesticides.

Termites will burrow through your hive and have been known to completely destroy bottom boards. Protect your hive by never letting it sit directly on the ground.

Spiders catch insects, so it stands to reason that you want to keep them well away from your bees. Knock down any webs you find near your hive, especially directly in front of it.

Mites are a serious problem. We’ve already talked about varroa mites, which are thought to have a possible link to CCD. They first appeared in the US in 1987 and can devastate colonies. It’s often hard to notice them until it’s too late, but one of the best ways is the sticky board. This is a sticky sheet underneath a mesh cover that can be used as a bottom board. Mites often fall off of bees and have to crawl back up into the hive, but with the sticky board they get stuck to the bottom. The mesh gives the much bigger bees something to stand on without getting stuck themselves.

Treatment for varroa mites ranges drastically. For a long time, Apistan strips were the only treatment available in the US, which created a serious resistance to it. Sometimes it still works fine, but other times it doesn’t. Thankfully there are other treatments now, such as Coumaphos strips, Apilife VAR, and Apiguard. All of these treatments have specific instructions that have to be followed regarding honey (to keep it from getting contaminated) so whichever you choose, be sure to follow the instructions on the label to the letter.

Tracheal mites are a much lesser problem than varroa mites, which is good, because they’re much harder to find. Tracheal mites lodge themselves inside the throats of bees and can only be seen if you remove the bee’s head and look at its throat under a microscope. Luckily, a lot of honeybees have a resistance to tracheal mites, meaning that even a colony that becomes infested will probably not be overrun. Tracheal mites cause a shorter lifespan and make it harder for bees to keep warm, which means the real risk is your colony not surviving the winter.

Pesticides

One of the most deadly hazards to bees actually comes from humans, in the form of pesticides. Bees are insects, after all, and chemicals designed to kill insects don’t make exceptions for the ones we like. Unfortunately, since honeybees will forage for miles, avoiding spraying on your own property often isn’t enough.

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It’s going to be very hard to convince your neighbors not to spray with pesticides. You are welcome to try, and you may succeed, but if you don’t, the next most important thing is to compromise and keep the lines of communication open. Ask them to let you know when they will be spraying. If it’s going to involve a lot of chemicals, you can move your bees at least three miles away from the area for the day. If that’s not feasible, You can drape wet burlap over the hives during the time of spraying to discourage your bees from going out.

If you have to spray on your property, be sure to opt for pesticides that are less long lasting. Many brands have less than eight hours of residual toxicity. If you spray in the evening, it should do its work of killing harmful pests overnight and be gone by morning when the bees begin foraging again.

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